1. Field of the Invention
The present invention relates to a seat belt buckle, and more particularly, the present invention relates to a sliding button type seat belt buckle installed on a seat belt of a motor vehicle seat, wherein a release button is pressed in a direction parallel to an inserting direction of a tongue into the seat belt buckle and thereby the tongue is unlatched from the seat belt buckle.
2. Description of the Related Art
Generally, a deluxe car has basic natures such as superior running capability, comfortable on-board feeling, high running speed and the like, and at the same time, is provided with a variety of safety measures capable of ensuring safety of an occupant.
Such safety measures include a seat belt, an airbag system, a safety steering column, a pyrotechnical seat belt retractor, and so forth. These safety measures are designed in a manner such that they can be automatically actuated upon heavy impact loading, to maximally protect an occupant.
Specifically, a seat belt is provided to a front seat or a rear seat of a motor vehicle and functions to prevent an occupant from being expelled out of the vehicle due to shock which is induced upon abrupt deceleration (for example, when the motor vehicle comes into collision).
A seat belt comprises a first belt part and a second belt part. Both ends of the first belt part are secured to upper and lower ends of a pillar panel of a vehicle. One end of the second belt part is secured to a bottom surface of the vehicle. A tongue is movably coupled to the first belt part. A seat belt buckle is fastened to the other end of the second belt part.
The tongue is of a metal plate-shaped contour and has a first aperture through which the first belt part passes and a second aperture into which a lock bar of the seat belt buckle can be inserted.
Seat belt buckles are divided into push button type seat belt buckles and sliding button type seat belt buckles depending upon a manner by which a release button is pressed.
First, the push button type seat belt buckle is generally applied to a rear seat of a motor vehicle, and a tongue is latched to or unlatched from the seat belt buckle by a lock bar which is moved in a vertical direction by virtue of a thin plate-shaped spring. Such push button type seat belt buckles are disclosed in U.S. Pat. Nos. 4,127,922, 4,064,603 and 4,998,328.
The sliding button type seat belt buckle is generally applied to a front seat of a motor vehicle. In the sliding button type seat belt buckle, a release button is pressed in the same direction as an inserting direction of a tongue into the seat belt buckle, and the tongue is latched to and unlatched from the seat belt buckle by a slider and a lock bar. Such sliding button type seat belt buckles are disclosed in U.S. Pat. Nos. 5,718,020, 5,271,129 and 4,899,424.
In the sliding button type seat belt buckle, a of longitudinal direction means a lengthwise direction of a body frame, a transverse direction means a widthwise direction of the body frame, and a vertical direction means a heightwise direction of the body frame.
In the sliding button type seat belt buckle, the tongue is latched to the seat belt buckle in a manner as described below. That is, as the tongue is inserted into the buckle, an ejector is moved rearward in the longitudinal direction, and an upper end of a locking lever is pivotally rotated downward by a predetermined angle about wings of the locking lever. Then, at the same time when the lock bar of the locking lever is inserted into an aperture which is defined in the tongue, the slider is fitted into a space which is defined between a lock pin and the body frame, whereby upward pivoting rotation of the locking lever is restricted by the slider.
Further, in the sliding button type seat belt buckle, the tongue is unlatched from the seat belt buckle in a manner as described below. By pressing the release button, the slider is removed from the space which is defined between the lock pin and the body frame, and then, the upper end of the locking lever is pivotally rotated upward by the predetermined angle by means of elastic force of a first spring. Thereafter, as the ejector is moved forward in the longitudinal direction by elastic force of a second spring, the tongue is discharged out of the buckle.
As shown in FIGS. 1 and 2, the conventional seat belt buckle comprises a body frame 10 which is fastened inside a casing (not shown) of the seat belt buckle, an ejector 60 which is capable of forcing a seat belt tongue (not shown) to be discharged out of the body frame 10, a locking lever 20 is having integrally formed therewith a lock bar 22, a slider 40 which slides on the locking lever 20, and a release button 50 which can push rearward the slider 40 to remove the slider 40 from a space defined between a lock pin 13 and the body frame 10, thereby enabling the lock bar 22 of the locking lever 20 to be released from an aperture defined in the tongue.
In the conventional seat belt buckle, the body frame 10 has a base plate 16 and upstanding side walls 17 which are bent upward from respective longitudinal edges (that is, longitudinally extending edges) of the base plate 16. An ejector sliding opening 12 is defined in the base plate 16 of the body frame 10, and hinge grooves 19 are formed at upper and substantially rear ends of the upstanding side walls 17 of the body frame 10. The lock pin 13 is fitted through trapezium-shaped holes 14 which are respectively defined in the upstanding side walls 17 of the body frame 10.
The lock pin 13 which is fitted through the trapezium-shaped holes 14, functions to retain the slider 40 in the space which is defined between the lock pin 13 and the body frame 10, and support the slider 40 in the heightwise direction of the body frame 10.
Moreover, the ejector 60 has a recessed portion which is formed at a front end of the ejector 60 to be brought into contact with the tongue. The ejector 60 is formed at both sides thereof with guide wings which slide on the base plate 16 along the ejector sliding opening 12 of the body frame 10. One end of a second spring 61 is secured to a rear end of the ejector 60. The other end of the second spring 61 is secured to a first projection 15 which is formed on a rear edge of the ejector sliding opening 12 of the base plate 16. Hence, the ejector 60 can be moved along the ejector sliding opening 12 in the longitudinal direction by elastic force of the second spring 61.
Also, the release button 50 is formed, at a center portion thereof, with a release projection 53 and, at both widthwise ends thereof, with two elongate portions 51. The release projection 53 projects from the center portion of an inner surface of the release button 50 to extend in the longitudinal direction. When the release button 50 is pressed, the release projection 53 functions to remove the slider 40 from the space which is defined between the lock pin 13 and the body frame 10. To this end, the release projection 53 is formed, at a rear free end thereof, with an inclined surface. In addition, the two elongate portions 51 also extend in the longitudinal direction from both widthwise ends of the inner surface of the release button 50, so that they are perpendicular to a plane of the release button 50. Each of the two elongate portions 51 is formed, at an upper end thereof, with a slit 52.
The two elongate portions 51 of the release button 50 which is configured in the above-described way, are respectively coupled to guide rails 11 of the upstanding side walls 17 of the body frame 10 in a manner such that the two elongate portions 51 can slide on the guide rails 11 in the longitudinal direction. The two elongate portions 51 cause the release projection 53 to push rearward the slider 40 in the longitudinal direction which slider 40 is interposed between the lock pin 13 and the locking lever 20, when the release button 50 is pressed, thereby to allow an unlatching operation of the tongue from the seat belt buckle to be implemented.
Engaging projections 18 are respectively formed on walls defining the hinge grooves 19 of the body frame 10 in a manner such that the engaging projections 18 project forward in the longitudinal direction. Wings 21 of the locking lever 20 are hingedly engaged into the hinge grooves 19. As described above, the locking lever 20 has integrally formed therewith the lock bar 22 which projects downward. The locking lever 20 is formed with a second projection 24. The other end of the first spring 42 which is secured at one end thereof to the slider 40, is secured to the second projection 24. The locking lever 20 also has at a rear end thereof integrally formed therewith legs 25. The legs 25 are bent substantially perpendicularly to a plane of the locking lever 20 to extend downward, thereby allowing the unlatching operation of the tongue from the seat belt buckle to be implemented. Here, when the ejector 60 is moved rearward in the longitudinal direction, the legs 25 of the locking lever 20 are brought into direct contact with a rear end surface of the ejector 60, thereby to undertake the unlatching operation of the tongue from the seat belt buckle.
The locking lever 20 has both side end surfaces 23 which extend straight. Guiders 41 of the slider 40 can slide on both the side end surfaces 23 of the locking lever 20. At front ends of the side end surfaces 23 of the locking lever 20, there are respectively formed stopper projections 23a. 
Further, the slider 40 has an inclined surface which can be brought into contact with the inclined surface of the release projection 53 of the release button 50 thereby to be pushed rearward.
The slider 40 is molded from polyoxymethylene-type acetal resin which is produced by polymerization of formaldehyde. When the locking lever 20 is moved to a latching position with the aid of the elastic force of the first spring 24, so as to latch the tongue to the seat belt buckle, the slider 40 forces the lock bar 22 of the locking lever 20 to be inserted into the aperture which is defined in the tongue.
In the conventional seat belt buckle, in order to unlatch the tongue from the seat belt buckle, the release button 50 is pressed. By this, the release button 50 is moved inward of the body frame 10. By the release button 50 which is moved in this way, the slider 40 is pushed rearward along both the side end surfaces 23 of the locking lever 20. At this time, the slider 40 is pivotally rotated upward along with the locking lever 20 by the elastic force of the first spring 42 through a predetermined angle. Thereupon, the lock bar 22 of the locking lever 20 is released from the aperture which is defined in the tongue. Accordingly, the ejector 60 discharges the tongue out of the body frame 10 while being moved forward by the elastic force of the second spring 61.
However, the conventional seat belt buckle constructed as mentioned above, suffers from defects in that, since the body frame 10 and the lock pin 13 are separately manufactured and then assembled, the seat belt buckle has relatively an infirm framework, and thereby, the lock bar 22 of the locking lever 20 can be unexpectedly released from the aperture in the tongue, whereby an abnormal unlatching phenomenon can occur as if the ejector 60 is actuated to discharge the tongue out of the seat belt buckle.
Also, in the conventional seat belt buckle, because the slider 40 does not have any vibration-absorbing means, the slider 40 can be deformed when the tongue is latched to the seat belt buckle or by heavy impact force induced upon a motor accident.
Further, in the conventional seat belt buckle, due to the fact that the release projection 53 is formed at the center portion of the release button 50, uniform and horizontal pressing force cannot be applied to the slider 40 through the release projection 53. Therefore, the slider 40 cannot slide on the locking block 20 along a true horizontal path, whereby a smooth and precise operation of the seat belt buckle is not guaranteed.
Moreover, in the conventional seat belt buckle, since the stopper projections 23a are formed at front ends of the side end surfaces 23 of the locking lever 20 so as to limit the sliding movement of the guiders 41 of the slider 40, in order to secure a sliding distance of the slider 40, a longitudinal length of the locking lever 20 cannot but be increased, whereby a compact structure cannot not be accomplished.
Furthermore, in the conventional seat belt buckle, in the case that the longitudinal length of the locking lever 20 is increased, downward pivoting rotation, through the predetermined angle, of the upper end of the locking lever 20 is slowed, whereby operational reliability of the seat belt buckle is deteriorated.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a seat belt buckle which includes a built-in type body frame, a locking lever having a compact structure and a slider having excellent vibration and shock-absorbing characteristic and dynamic stability, thereby accomplishing durability and operational reliability.
Another object of the present invention is to provide a seat belt buckle which possesses a switching structure using a hall sensor so as to allow an occupant to visibly confirm latched and unlatched conditions of the seat belt buckle, thereby providing information about an operational status of the seat belt buckle to the occupant.
Still another object of the present invention is to provide a seat belt buckle in which main internal structural components such as a body frame, and so on, are firmly and stably maintained by a rigid coupling structure of upper and lower casings.
In order to achieve the above objects, according to one aspect of the present invention, there is provided a seat belt buckle comprising: a body frame; a release button slidably coupled to the body frame for unlatching a seat belt tongue from the seat belt buckle; a locking lever capable of being pivotally rotated about wings by a predetermined angle; a slider for supporting and fixing the locking lever; and an ejector for pushing the tongue in a longitudinal direction which is a lengthwise direction of the body frame; the body frame having an arch-shaped supporting beam which is integrally formed with the body frame in a manner such that the supporting beam is erected in a vertical direction, the supporting beam serving to limit movement of the slider and increase structural rigidity of the seat belt buckle; the slider having a width which is greater than that of the body frame and possessing shock-absorbing means for increasing durability of the seat belt buckle, the slider being formed with inclined projections; and the release button having at least two release projections which are formed with inclined surfaces which are in turn brought into contact with the inclined projections of the slider.